Kidney Week

Abstract: TH-PO093

Loss of Proximal Tubular Krüppel-Like Factor 6 Is Protective Against Renal Injury

Session Information

• AKI: Inflammation, New Technologies, Omics
  October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

• 103 AKI: Mechanisms

Authors

• Piret, Sian, Stony Brook University, Oyster Bay, New York, United States

Sian Piret,

• Guo, Yiqing, Stony Brook University, Oyster Bay, New York, United States

Yiqing Guo,

• Revelo Penafiel, Monica Patricia, University of Utah, Murray, Utah, United States

Monica Patricia Revelo Penafiel,

• Mallipattu, Sandeep K., Stony Brook Medicine, Stony Brook, New York, United States

Sandeep K. Mallipattu,

Background

Transcriptional regulators of DNA-damage pathways leading to kidney fibrosis are relatively unknown. Krüppel-like factor 6 (KLF6), a zinc finger transcription factor, has diverse roles in various tissues. KLF6 is highly expressed in the proximal tubule (PT) and upregulated in renal ischemia-reperfusion injury and sepsis models, but its specific role in PT DNA damage and tubulointerstitial fibrosis is unknown. Our aim was to investigate the role of PT KLF6 in the setting of DNA damage, using the PT-specific DNA damaging toxin aristolochic acid I (AAI).

Methods

PT-specific Klf6 knockdown (Klf6^PTKO) mice were generated by breeding Klf6^fl/fl and Pepck-Cre mice. Klf6^fl/fl littermates were used as controls. Mice were given 3mg/kg AAI or vehicle DMSO i.p. every 3 days for 3 weeks (active phase), followed by 3 weeks without injections (remodeling phase), and euthanized. Renal damage was assessed by: serum creatinine and urea nitrogen (SUN); histology (H&E, PAS and trichrome staining with blinded scoring for inflammation and fibrosis); IF for deposition of collagen 1A1 (COL1A1); and qRT-PCR for vimentin and E-cadherin expression. RNA-Seq was undertaken in active and remodeling phase samples. Data were analyzed using ANOVA with corrections for multiple comparisons.

Results

AAI caused renal damage and significantly increased serum creatinine and SUN in all mice. These were significantly lower in Klf6^PTKO mice versus Klf6^fl/fl mice in the acute phase, with lower vimentin expression, and preserved PT area and E-cadherin expression. In the remodeling phase, Klf6^PTKO kidneys had maintained weight, preserved PT area and less inflammation, fibrosis, COL1A1 deposition and vimentin expression, compared to Klf6^fl/fl kidneys. RNA-Seq combined with ENCODE ChIP-Seq data showed that many integrin signaling components that contribute to fibrosis were upregulated by AAI in Klf6^fl/fl mice, which was reversed in Klf6^PTKO mice with AAI, and contain KLF6 binding sites. Likely protective genes were upregulated by AAI and upregulated further in Klf6^PTKO mice, e.g. Gas6, which has a predicted KLF6 binding site.

Conclusion

PT-specific loss of KLF6 protects against renal injury and fibrosis in the setting of DNA damage. This may have relevance for DNA damaging nephrotoxic chemotherapeutic drugs e.g. cisplatin.

Funding

• NIDDK Support